Mold supporting structure for casting machine



NOV. 19, 1968 5|EGER 3,411,567

MOLD SUPPORTING STRUCTURE FOR CASTING MACHINE Filed June 15, 1966 2 SheetsSheet 1 FIG.

INVENTOR MAURICE P. SIEGER HIS ATTORNEY M. P. SIEGER 3,411,567

MOLD SUPPORTING STRUCTURE FOR CASTING MACHINE Nov. 19, 1968 2 Sheets-Sheet 2 Filed June 1 5, 1966 INVENTOR MAURICE P. SIEGER BY jL Q 72:2;

HIS ATTORNEY United States Patent 3,411,567 MOLD SUPPORTING STRUCTURE FOR CASTING MACHINE Maurice Paul Sieger, Upper St. Clair Township, Pittsburgh, Pa., assignor to United Engineering and Foundry Company, Pittsburgh, Pa., a corporation of Pennsylvania Filed June 13, 1966, Ser. No. 557,089 7 Claims. (Cl. 164341) ABSTRACT OF THE DISCLOSURE The present disclosure relates to an article-casting machine and, more particularly, to an improved construction for supporting one or more molds thereof. The present disclosure provides a mold clamping arrangement that includes a mechanical arrangement for maintaining the molds in their operative casting position which is not subject to power failure, and wherein the construction compensates for the substantial differential between the pressure at the bottom and at the top of the molds.

In one form the present invention provides in an article-casting machine having at least a pair of opposed molds, a first carriage, a mold carried by said first carriage, a second carriage, a mold carried by said second carriage, said mold forming at least a part of a mold cavity, at least one of said carriages movable towards and away from the other and into and out of a casting position, respectively, mechanical means, preferably being of a self-locking type, for positioning said movable mold in said casting position relative to the other mold and for preventing separation thereof during casting, said mechanical means having a mold connecting element arranged on the lower side of the central longitudinal axes of said molds, two groups of yieldable means, such as springs, carried by each carriage, said yieldable means of each group being spaced longitudinally of said molds and each group being located on opposite sides of the longitudinal central axes of said molds, said yieldable means arranged towards the bottom of said casting molds having a substantially larger total resistant capacity than the group of springs arranged toward the top of said casting molds.

A further object of the present invention is to provide for each of the aforesaid carriages a flask having at its bottom a mold supporting surface, means for holding the molds with respect to the flasks, said flasks being held in a casting position by said mechanical means, said springs associated with said flasks, and means for prestressing the springs of each group commensurate with the varying degree of deflection imposed upon said casting molds and flask during casting.

Background of invention The present invention is addressed to a problem, which, while common to many types of casting machines, for purposes of discussion only, is identified with a mold arrangement of a bottom pressure casting machine of the type shown in US. Patent No. 3,015,863 that issued on Jan. 9, 1962 in the name of C. F. Strom et al. In molds of this type the article to be cast is formed by arranging two side molds in a casting position separated by the thickness of the article, the cavity thus formed is further enclosed by two end and bottom and top molds. Into the cavity there is discharged pressurized molten metal which on solidification is formed into the cast article.

In prior arrangements it was customary to maintain the molds in the casting position by fluid means, such as hydraulic piston cylinder assemblies. Such means were Patented Nov. 19, 1968 particularly required with respect to the relatively long side molds, since they had the tendency to deflect along their longitudinal axes so that the cylinder assemblies Were arranged in spaced relation to counteract this deflection. In such a construction, on the failure of the hydraulic pressure, the molds could not be maintained in their desired position and the casting was lost. Because of the frequent occasions that normally can give rise to failure of the hydraulic pressure, a need for an improved mold clamping arrangement which would be free from inadvertent failure of the power source was obvious. Any design that might eliminate the aforesaid objection, of course, must take into account the inherent condition in such casting machines, wherein there is created a substantial sphenostatic eflect at the bottom of the molds so that the construction must be able to compensate for the subsantial difference of pressures existing between the top and bottom of the molds.

Drawings Description of invention With reference to the drawings and first with respect to FIGURE 2, there is illustrated a traversing carriage 10 and a similar but opposed traversing carriage 11. These carriages are provided with wheels 13 and 14 to allow them to be moved towards and away from each other a predetermined distance. In the particular case the wheels run over two pairs of rails 15 and 16, it being understood that the rails 15 and 16 themselves may, in a given case, be supported by a movable carriage, this carriage being adapted to be brought into the casting station which will include a molten metal pressure vessel.

Returning to the carriages 10 and 11, it can be assumed that they generally are identical although, with respect to the carriage 10, there are some differences that will be noted as this description proceeds. The carriage 11 supports a one-piece flask 17 which extends along the longitudinal axis of the carriage and is supported by projections 17a at the bottom thereof and by a hook 17b at the top. The flask is adapted to support a sectionalized graphite mold 18 which forms one side of the casting cavity, the mold 18 being supported by the flask by reason of a projection 19 arranged at the lower end. The mold in addition is retained from moving relative to the flask by end keeper plates 20, shown only in FIGURE 1,

in addition to a vertically arranged keeper plate 21 shown in FIGURE 2. While the flask engages and is supported by the bottom of the carriage 10, it is permitted to move relative to the carriage and is actually separated from the vertical portion of the carriage by two groups of springs 23 and 24. As noted previously, the springs at the bottom are spaced below the central longitudinal axis of the mold and are of greater capacity than the upper springs 23, this increased capacity being needed at the bottom in view of the sphenostatic condition that is created in the solidification of the casting.

At this point reference is made to the carriage 10, which, as noted before, is similar generally to the carriage 11. It will be noted, however, with respect to the carriage 10 that it has a somewhat narrower mold 25 which is received in a flask 28, the flask being supported in a way similar to what is described with respect to the flask 17. The flask 28 is also provided with two groups of opposed springs 26 and 27 similar to the springs 23 and 24 of the carriage 11. On the carriage the-re is provided the top mold 31 which closes the cavity at the top as does a lower mold 32, the lower mold, however, being arranged independent of either carriage 10 or 11.

The carriages are shown in their operative position, thus in FIGURES 1 and 2 the actual casting cavity is as shown. The carriages are adapted to be held in this position by a mechanical self-locking device which is one of the important aspects of the present invention, In this connection, reference is made to FIGURE 1 and it will be noted that on both sides of the carriage 11 there are provided worm-wheel units 33 and 34, the worms of which are adapted to be driven by a common motor 35 carried on the carriage 11, which units 33 and 34 have horizontally arranged screws 36 and 37 including enlarged heads which are received and held in boxes 38 and 39. It should be pointed out that the ratios of the gearings of the worm-wheel units are very high of the order, for example, of :1 which, in combination with the screws having a small thread angle will have the positive advantage of being self-locking under the pressure of the casting process. Thus, it can be seen by operating the motor 35, the carriage 11 is brought positively and forcibly in a direction towards the carriage 10 and the molds 18, 25, 31 and 32 and in addition, the end molds 41 and 42 are brought into a sealed condition.

It should be noted with respect to FIGURE 1 that the side molds 18 and 25 are made up in a plurality of pieces which are pressed together longitudinally by tension bolts 43.

FIGURE 2 illustrates that the wheels 14 at the front of the carriages 10 and 11 are engaged with brake shoes 44 which are operated by solenoids 45. The solenoid and brakes are provided so that when the casting is completed and the motor is operated to separate the molds, only one of the carriages 10 or 11 will move relative to the other one. Thus, this allows the cast article to be maintained in a fixed relation relative to the equipment employed to remove the casting from the casting machine.

One important feature of the present invention is to provide a very stable construction for the carriages 10 and 11 when subject to the forces developed during the casting process. Since the reaction forces are taken in the carriages through the shafts 36 and 37 unless the carriages are constructed properly, there will be an objectionable rotating action imposed thereon. To counteract this, the carriages are each constructed with a longitudinal beam 47, the longitudinal axes of which are below the horizontal axes of the carriage proper and coincide with the axes of shafts 36 and 37. This positions the center of gravity of the carriages toward the bottom thereof and substantially stabilizes the carriages. This offset construction also, as noted above, assists greatly in counteracting the increased pressure condition that is created at the bottom of the molds. In the illustrated form the spacing of the springs 23 and 24 relative to the axes of the beam 47 is at a 2:1 ratio. In another construction where the length of the mold is less, the ratio was fixed at 3:2.

In accordance with the provisions of the patent statutes, I have explained the principle and operation of my invention and have illustrated and described what I con sider to represent the best embodiment thereof. However, I desire to have it understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically illustrated and described.

I claim:

1. In an article-casting machine comprising a first and second carriage movable relative to each other and forming part of an article-casting machine;

a separate mold carried by each carriage,

a mechanical means for bringing at least one of said carriages into a casting position and in which position during casting a greater pressure is exerted on the bottom of the molds than on the top thereof,

two groups of self-contained non-fluid yieldable means carried by each of said carriages arranged on either side of the longitudinal axes of said molds and in a manner to resist the mold pressure, and

wherein said groups of yieldable means associated with the bottom portion of the molds have a greater total resistance than the groups of yieldable means associated with the top thereof.

2. In an article-casting machine according to claim 1 in which said mechanical means includes a pair of self-locking devices, and

means for connecting together said devices for simultaneous operation.

3. In an article-casting machine according to claim 2 wherein each carriage comprises a beam arranged below the longitudinal axes of the carriages, and wherein the axes of said pair of self-locking devices coincide with the longitudinal axes of the beams.

4. In an article-casting machine according to claim 3 wherein said yieldable means comprises springs and wherein said longitudinal axes of said beams are closer to the lower groups of springs than the upper groups.

5. In an article-casting machine according to claim 3, means for selectively holding said carriages in their operative casting positions.

6. In an article-casting machine according to claim 4, wherein each mold is supported by a flask carried by one of said carriages, and wherein said springs engage said flasks and are arranged between the flasks and the carriages.

7. In an article-casting machine according to claim 6, including means forming part of said carriages for carrying said flasks in a manner that will allow relative movement with respect to said carriages and springs.

References Cited UNITED STATES PATENTS 1,700,341 1/1929 Travis 164341 1,872,085 8/1932 Korsmo 164341 2,756,473 7/1956 Anderson et a1 164-339 2,921,355 1/1960 Gould et a1. 18-43 X 3,159,875 12/1964 Stutz et al. 18-5 I. SPENCER OVERHOLSER, Primary Examiner.

E. MAR, Assistant Examiner. 

